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Kemia-Kemi 10 (1983) 11: 982-983
Dr. A. Parfait * Centre de Researches Agronomiques des Antilles et de la Guyane Petit-Bourg, Guadeloupe
*Dr. A. Parfait is the head of Centre de Recherches Agronomiques des Antilles et de la Guyane, Station de Technologie des Produits Végétaux, INRA, Petit-Bourg (Guadeloupe). Dr. Parfait stayed for two months as a guest researcher at the Research Laboratories of the State Alcohol Monopoly (Alko Ltd.). The paper is based on his lecture given at Alko, Helsinki September 9th, 1982.
In each country the production of alcoholic beverages has ancient origins. Guadeloupean rums, however, do not appear to be an indigenous beverage; they are linked with recent economic and social periods. This is reflected in the circumstances surrounding the production of rum as well as in technological evolution.
The production of rum
Located in the central part of the Caribbean Basin, Guadeloupe is an archipelago consisting of seven major islands. “Basse-Terre” is a volcanic massif, “Grande-Terre” is a limestone plateau, while in the south there are “Marie-Galante” and “les Saintes”, in the East, “la Désirade”, and in the North, “Saint-Barthélemy” and “Saint-Martin”. Its general location is 16° North and 61° West. Lasserre (1961) made a very detailed human and geographical study of Guadeloupe. In spite of the fact that it covers an area of less than 1,800 square kilometres, its contrasts in climate are quite pronounced. The main populating of the islands did not really begin until the 18th century, although they were inhabited prior to their discovery in 1493 by Christopher Columbus.
It is thought that sugar cane originated in the Himalayan valleys. This plant was introduced very early, by the Spanish, since it is mentioned by historians such as the fathers Du Tertre (1667) and Labat (1724). Numerous works have been dedicated to sugar cane, on biology Van-Dillenijn (1960) and Fauconnier (1970), on sugar production Honing (1963), and on its by-products Paturau (1982). Today, sugar cane production in Guadeloupe is undergoing a number of technical, economic and social difficulties. These are particularly related to cultivation techniques (fertilization, choice of varieties) and to harvesting organization (mechanization). The decline in sugar cane production for Guadeloupe (from 1,685,000 tonnes in 1960 to 840,000 in 1982) concerning many other islands of the Caribbean Basin as well, and we can witness at the same time a transfer of sugar production to the Latin-American continent. Generally, it is estimated that 100 tons of cane provide:
—11 tonnes of sugar at 98.5 Pol
—3 tonnes of molasses at 85° unrefined and 1.47 density
—2 tonnes of sediment at 80% humidity
—0.3 tonnes of ash
—120 tonnes of vapour at 135°C
—4 tonnes of surplus bagasse at 50% humidity
—1500 kwh of surplus electricity
At the beginning of colonization the main agricultural crops for export were tobacco, cotton and indigo. At the end of the 17th century, prohibitive duties affected the European markets for Guadeloupean tobacco. At the same time, thanks to the use of a sugar whitening technique, conditions were created enabling the production of sugar cane to make great strides. According to Lasserre (1961), the number of sugar factories increased from less than 40 in 1650 to 403 in 1830 (each of these installations in a sugar-producing setting could produce an average of 100 tonnes of sugar per year.
Rum was produced in the vinegar factories annexed to the sugar factories. At the end of the 18th century, it was generally estimated that the revenue from the manufacture of spirits could represent 1/15 to 1/4 of total returns. The introduction of the steam engine into the sugar factories saw the first great concentration of units of production. At the same time, there was a differentiation in the use of raw materials. Sugar factories associated with sugar farming with molasses while the agricultural distilleries use cane juice. At the end of the 19th century, conflicts in Europe and the philloxera crisis that affected the vineyards of France greatly contributed to the expansion of the production of rum. The French state was forced to intervene in order to organize competition between on the one hand, the rums and other French spirits and, on the other, the production of rum in factories and in agricultural distilleries. For this purpose the contingent system was instituted in approximately 1920.
[Vinegar factory is a very old term for distillery.]
During the last 50 years, the rum markets have evolved as a result of several technical and economic factors. Following the works of Arroyo (1945) in Puerto Rico, a technology was proposed for the production of light-bodied rums. The common agricultural policy of the European Economic Community should have been a positive element for the sugar production in the French Antilles as it is for the European sugar beat. Sugar was then classed as an agricultural product and the rums as industrial products. The LOME agreements opened in part the European markets to the rum production of the A.C.P. (Africa, Caribbean, Pacific) countries. All these factors greatly stimulated the producers in Guadeloupe to turn to the manufacture of light-bodied rums rather than the traditional production essentially centered on industrial rums from molasses and agricultural rums. Nevertheless, a certain decrease in the production of rum in Guadeloupe has occurred. In 1980, 6.78 million litres of molasse rum and 3.14 million litres of cane rum were produced. This total of 9.91 million litres is ca 10% less than that in 1970. A decline in the export of the traditional formula (industrial and agricultural rum) has been observed as well as the stronger position held by cane spirits for the manufacture of light-bodied rums. Finally, problems in legislation stemming from the different definitions of rums in different countries and the necessity of providing qualities in accordance with the tastes of consumers have intensified the difficulties in Guadeloupe. A research effort therefore seemed useful to adapt technology to rums in the French Antilles. Kervegant (1946) has made a most interesting review.
[I have never heard the idea that LOAM was tied to the rise of light bodied rums of the 1970’s.]
Research into rums
Molasses is the raw material most used in the manufacture of rums. Different physiochemical treatments can improve the fermentability of molasses in sugar cane. During the disappearance of sugar-producing environmens, we have observed that some producers turned to fermenting all the juices extracted from the sugar cane. There has never been however a varied selection in the sugar cane based on the rum aptitudes. We have, in fact, very little biochemical information on the possibilities of utilizing the different fractions of the raw material. Certain reducing sugars are not suitable for fermentation in molasses, but their exhaustive inventory has not yet been made. It is necessary to supplement the musts of molasses and of cane juice, either with ammonium sulphate or urea, because a good portion of the nitrogenous fraction of molasses is not assimilable. The influence of the phenolic compounds, the terpenes and the sulphur compounds on the aroma is not well known, even though qualitative and quantitative investigations on these have already been done.
[“all the juices” implies “high test” molasses as best I can tell. The rum aptitude idea appears in other INRA papers. They eventually isolated yeast optimized for rum production, but I am not aware of any modern cane varieties being revealed as optimized for rum. Most of the ideas on the best varieties for rum quality are from the early 19th century.]
[Phenolic compounds & terpenes very likely relates to the rum oil phenomenon. The INRA did publish one paper on sulfur metabolism in 1989.]
The first observations made on the fermentations of molasses and cane juice showed that the active yeast was Schizosaccharomyces pombe. It still persists in some fermentations, leading to considerable content of aromatic impurities. An average composition of this type of product for which it can be thought that a mixed fermentation has taken place is presented in the Table. Clostridium saccharobutyricum seems to be an important bacterium in the mixture of flora, but its precise determination has not yet been formulated. Today, the species most widely seen in the musts is Saccharomyces cerevisiae, because it is more rapid than Schizosaccharomyces pombe.
[This framing is interesting and is seldom noted. The very first observations of rum yeasts in any ferments were fission yeasts. This was by Percival Greg in Jamaica and multiple Dutch scientists in Batavia. Dr. Parfait notes a Clostridium, but I am not aware that the INRA ever investigated them.]
In selecting yeasts with good rum aptitudes , the main criterion initially was fermentation efficiency, that is to say, the maximal quantity of ethanol produced per unit of sugar. Attention was then given to stocks tolerant to ethanol; it was observed that they were found in both Saccharomyces cerevisiae and Schizosaccharomyces pombe. A third path aimed at the creation of yeasts for rum. We have compared wine yeasts, baking yeasts and stocks selected in the molasses-based and cane juice-based natural settings.
They all belong to the species Saccharomyces cerevisiae. The physiological characteristics, the composition (contents of nitrogen and reserve carbohydrates), and the influence of organic acids seem to distinguish the latter as true rum yeasts in comparison with the former.
[The logic here is oddly setup. The first sentence of the new paragraph implies rum aptitude is found with a budding yeast then the second sentence implies fission yeast, being the latter, are true rum yeasts. What the INRA put on the market was eventually a budding yeast yet most of their other papers denote a fission yeast as the true rum yeast.]
To obtain a quality spirit with the distillation columns of the father Labat type (which were similar to the stills of charentes), fractional distillation had to be resorted to. On the technical level, creole columns have been designed, above every thing else, to allow only slight losses of ethanol in the vinasse and to furnish a spirits throughout the distillation and at the exit of the column having the average composition of rums. In order to obtain spirit in conformity with a standard and having a low concentration of fusel oil, rectification has become a distillation technique widely used in the manufacture of light-bodied rum. In the French Antilles, where rectification is not authorized, adjustments made to the distillation columns permit the extraction of most of the impurities from some plates.
[The logic here is also hard to under stand. Labat stills are just pot stills so the word column doesn’t fit. Rectification is also not precisely applied. Does it imply inline fusel oil separation which was briefly controversial in Bourbon production? Does it imply a distillation ABV not to be exceeded? What is likely is that a distillation ABV is not to be exceeded so fusel oil separation is practiced on certain plates where it accumulates and the ethanol is returned to the column. Lip service is paid to the spirit of the law. The alternative would be conducting fermentation is a way to minimize fusel oil such as having longer duration, cooler ferments that features yeasts that are below average fusel oil producers such as fission yeasts. This fermentation strategy is described across many INRA papers.]
Techniques for the aging of rums have been widely borrowed from those for cognacs and armagnacs. Recent work on the suitability of different woods originating in temperate (oak) and tropical (angelica) countries will certainly bear fruit in this stage of rum technology. French production of rums holds a special position in the world production of rums widely dominated by light-bodied rums. Their compositions are indicated in the Table. From the technical point of view, the essential difference is reflected in the control. In the French legislation the spirits from cane and from molasses must, at the exit from the column, have the caracteristics of rums. Elsewhere, they can undergo subsequent treatments. French aged rums are rums that have undergone a well defined aging in oak barrels. We have undertaken in the last few years many works on the technology of French rums and on their organoleptical characteristics. These products have benefitted from recent analytical advances, and there are more and more references on their composition, e.g. Cavazza (1975), Mesley (1975), Liebich (1970).
[I have never found any of the INRA papers on aging in tropical hardwoods.]
The production of French rums represents less than one tenth of the world production of rums. Guadeloupe is an important area of manufacture of these French rums. An important research effort in which INRA is actively participating aims at making it a product of international quality.
Rum is not an indigenous production in Guadeloupe. Its production is linked to the history of colonization. Research is being conducted, in France and elsewhere in the world, in order to improve the quality of French rums.
Lasserre, G. (1961) — La Guadeloupe. Tome I. Le milieu naturel, l’héritage du passé p. 1-447 Chez Union Française d’Impression (Bordeaux). Tome 2. Les régions géographiques, les problèmes guadeloupéens p. 448-1135 Chez Union Française d’Impression (Bordeaux).
Du Tertre, R.P. (1667) — Histoire générale des Antilles. 3 vol. Édition société d’histoire de la Martinique en 1958.
Labat, R.P. (1724) — Nouveau voyage aux iles françaises de l’Amérique 6 Vol. Édition G. Cavalier à Paris.
Bonneton-Koussoula, A. (1981) — Contributions à l’étude de l’économie sucrière en Guadeloupe. Document Inra Centre des Antilles 154 p.
Arroyo, A. (1945) — Studies on Rum 271 p. Research Bulletin n° 5 – Agricultural Experimental Station – University of Puerto Rico.
Honing, P. — Principles of Sugar Technology. Vol. 1, 1953, Vol. 2, 1959, Vol. 3, 1963; Elsevier – Presse.
Van Dillenijn, C. (1960) — Botanique de la canne à sucre. Édité par H. Veenman.
Paturau, J.M. (1982) — By-products of the Cane Sugar Industry 336 p. Elsevier Scientific Publishing Company ISBN 0444 420 34-7.
Kervegant, D. (1946) — Rhums et eaux-de-vie de canne 510 p. Les éditions du Golfe à Vannes (France).
Fauconnier, R. and Bassereau, D. (1970) — La canne à sucre 500 p. Édité par G.P. Maisonneuve et Larose à Paris.
Cavazza, G. Annales de technologie agricole. 24 (1975) 247.
Mesley, R.J. Annales de technologie agricole. 24 (1975) 361.
Liebich, A.M. Chromatogr. Sci. 8 (1970) 257. [Analysis of the Flavor of Rum by Gas-Liquid Chromatography and Mass Spectrometry]